Dielectrics for ozone-generating apparatuses

ABSTRACT

An assembly for an ozone-generating apparatus consisting of a cylindrical tube of constant thickness which is provided with an internal metal coating and which is characterized in that said tube, which is made of glass or of any other suitable material able to be used in an ozone-generating apparatus, is essentially open at both ends but fitted at one end (or both ends in some cases) with a removable plug which is formed of ozone-resistant insulating material and provided with an axial passageway. A metal rod is adapted to pass through the passageway and serves to apply voltage to the metal coating which is formed on the internal face of the dielectric tube, the length of said coating being slightly smaller than the length of said tube. The rod is of smaller diameter than the passageway in order to admit cooling air into the dielectric tube. The plug may either be inserted into the corresponding extremity of the tube of insulating material or placed over said extremity.

United States Patent Louboutin 1 June 20, 1972 [54] DIELECTRICS FOROZONE- Degremont, Societe Generale DEpuration et D'Assainissement,Rueil-Malmaison, France [22] Filed: June3, 1970 [21] Appl.No.: 42,915

[73] Assignee:

Primary Examiner.lohn H. Mack Assistant Examiner-Neil A. KaplanAttorney-Wenderoth, Lind & Ponack [57] ABSTRACT An assembly for anozone-generating apparatus consisting of a cylindrical tube of constantthickness which is provided with an internal metal coating and which ischaracterized in that said tube, which is made of glass or of any othersuitable material able to be used in an ozone-generating apparatus, isessentially open at both ends but fitted at one end (or both ends insome cases) with a removable plug which is formed of ozone-resistantinsulating material and provided with an axial passageway. A metal rodis adapted to pass through the passageway and serves to apply voltage tothe metal coating which is formed on the internal face of the dielectrictube, the length of said coating being slightly smaller than the lengthof said tube. The rod is of smaller diameter than the passageway inorder to admit cooling air into the dielectric tube. The plug may eitherbe inserted into the corresponding extremity of the tube of insulatingmaterial or placed over said extremity.

6 Claims, 4 Drawing Figures PATfNTEnJuuzo m2 SHEET 10F 2 Inventor ROBERTLOUBOUTIN Bwmmw flu Attorneys PATiNTEnJunzo I972 SHEET 2 OF 2 InventorROBERT LOUBOUTIN mwmm Attorneys DIELECTRICS FOR OZONE-GENERATINGAPPARATUSES This invention relates to assemblies for ozone-generatingappliances.

It is a known practice in the case of ozonizers of the tube type to makeuse of a dielectric consisting of a glass cylinder having a constantthickness and closed at one extremity by an end wall which isadvantageously in the form of either a spherical segment, or a cone or aflat base whilst the other extremity is open and provided withcorrugations. Said cylindrical glass tube is lined or coated internallywith metal which is connected by means of a brush to one of theterminals of a highvoltage alternating-current source whilst the secondterminal is connected to ground. Said glass tube is placed within agrounded coaxialmetal cylinder whilst centering devices serve tomaintain a constant distance or socalled discharge gap between the glasstube and the metal tube.

This known assembly forms a capacitor in which the capacitor plates areformed by the metal tube and the metal deposited on the glass tubewhilst the dielectric is constituted by the glass tube itself and by theair contained in the discharge gap. Ozone is formed within this gap fromatmospheric oxygen under the action of the applied high-voltage.Production of ozone is thus carried out continuously by renewal of theoxygen within the discharge gap, this being achieved by blowing a streamof air from the open end of the tube towards the closed end. Theevolution of heat which is found to take place during the operation ofthis known device can cause destruction of the formed ozone and thedischarge gap must therefore be cooled by circulating water around themetal tube.

It is also known that, in the case of a given ozonizer and the samevalue of applied voltage, the production of ozone is the greater inproportion as the capacitance of the capacitor of the type described inthe foregoing is high. A high capacitance is obtained by employing glasswhich has a small thickness and high permittivity but the dielectricstrength of which must nevertheless be of sufficiently high value to becompatible with the voltage applied thereto. Glass tubes having aconstant small thickness of the type which has just been described canbe fabricated from glass having high permittivity but this is a costlyand difficult process. In particular, while a practically constantthickness can be obtained in the cylindrical portion of the tube, anappreciable reductionjn thickness in the vicinity of the end wallusually appears. This reduced thickness results in excessive mechanicalfragility of the end portion of the tube and in a substantially loweringof its dielectric strength.

The object of this invention is to provide assemblies forozone-generating appliances which satisfy practical requirements moreeffectively than the dielectrics which have been employed for the samepurpose up to the present time, especially insofar as the constructionaldifficulties which were inherent in dielectrics of the prior art now nolonger arise and the cost price of the dielectrics according to thepresent invention is appreciably lower than that of comparabledielectrics of the prior art.

This invention is concerned with a dielectric for an ozonegeneratingapparatus, said dielectric being constituted by a cylindrical tube ofconstant thickness provided with an internal metal coating andcharacterized in that said tube, which is formed of glass or of anysuitable insulating material for use in an apparatus for the productionof ozone, is open at both ends.

In an advantageous form of embodiment of the dielectric in accordancewith the invention for use in ozone-generating apparatuses, one end ofthe tube of insulating material is closed by means of a removable plugof ozone-resistant insulating material, said plug being provided with anaxial passageway through which is passed a metal rod for applyingvoltage to the metal coating which covers the internal face of thedielectric.

In a preferred arrangement of this form of embodiment, the passagewayfor the metal rod which serves to apply voltage to the internal metalcoating of the dielectric has a diameter which is slightly larger thandiameter of said rod.

In another preferred arrangement of the same fonn of embodiment, theplug is fitted with a seal which is advantageously circular and fonns aspring in order to ensure positional maintenance of the plug inconjunction with the end of the tube which is sealed off by means ofsaid plug.

In a third preferred arrangement of this form of embodiment, the plug isprovided externally with corrugations which are intended to preventflashover phenomena.

In an advantageous fonn of embodiment of the plug in accordance with thepresent invention, said plug is inserted into the correspondingextremity of the tube of insulating material.

In a further advantageous form of embodiment of the plug in accordancewith this invention, the plug is placed over the corresponding extremityof the tube of insulating material and is provided in this case withadditional lateral passageways for establishing a communication betweenthe chamber into which air is admitted and the discharge gaps.

In a particular form of embodiment of the dielectric as contemplated bythe present invention for use in an ozonegenerating apparatus, the otherextremity of the tube of insulating material is also closed by means ofa plug of the type hereinabove described.

In yet another advantageous form of embodiment of the dielectric forozone generators as contemplated by the present invention, the internalmetal coating of the tube of insulating material is deposited over alength which is preferably smaller than the length of said tube.

In a preferred arrangement of this form of embodiment of the dielectricfor ozone-generating apparatuses as contemplated by the presentinvention, the ends of the tube of insulating material are unmetallizedin the case in which the length of the internal metal coating of thetube is smaller than the length of said tube.

In another preferred arrangement of said form of embodiment, the ends ofthe tube of insulating material are unmetallized over distances whichare substantially equal to each other.

In addition to the arrangements which have just been mentioned, theinvention further comprises a number of other arrangements which willbecome apparent from the following description.

The present invention is directed in particular to dielectrics forozone-generating appliances in accordance with the foregoingarrangements and the elements which are suited for the manufacturingofsaid dielectrics.

A better understanding of the invention will be gained from thecomplementary description which now follows below, reference being madeto the accompanying drawings, in which:

FIG. I is an axial sectional view of one form of embodiment of thedielectric according to the present invention for use in anozone-generating apparatus;

FIG. 2 is a fragmentary axial sectional view of another form ofembodiment of the dielectric according to the invention for use in anozone-generating apparatus;

FIG. 3 is an axial sectional view of a third form of embodiment of thedielectric according to the invention for use in an ozone-generatingapparatus;

FIG. 4 s an axial sectional view corresponding to FIG. 3 and showinganother form of embodiment of the dielectric according to the presentinvention for use in an ozone-generating apparatus.

It must be clearly understood that both the following description andthe drawings to which it refers are given solely as an explanatoryillustration of the subject-matter of this invention and are notintended to imply any limitation whatsoever.

The dielectric which is intended for an ozone-generating apparatus andillustrated in FIG. 1 is made up of a cylindrical tube 1 of constantthickness, said tube being formed of glass or any other insulatingmaterial which can be employed in an apparatus for the production ofozone. The tube is open at both ends and is provided with an internalmetal coating 2 over a length l which is preferably smaller than thelength L of the tube, the extremities 3 of said tube being unmetallizedover distances which can advantageously be equal at each end.

One of the open ends of said tube 1 is closed by a removable plug 4which is made of an insulating material affording resistance to ozonesuch as porcelain, glass, polyvinyl chloride, hypalon, and so forth.Said plug is provided with an axial passageway 5 through which is passedthe rod 6 of the brush 7 (or the like) which is employed for applyingvoltage to the metal coating 2 formed on the internal face of thedielectric. Said plug is advantageously fitted with a seal 8 which canbe of the O-ring type and forms a spring, said seal being intended tomaintain the plug 4 in position within the dielectric tube 1. Externalcorrugations 9 which are formed on the plug 4 serve to prevent flashoverphenomena. The dielectric tube 1 which is sealed off at one end by meansof the plug 4 is mounted in known manner within the interior of acoaxial and grounded steel tube 10 and is positionally maintained withinthis latter by means of centering devices 11 which maintain a constantdischarge gap 12 between said tube 1 of insulating material and themetal tube 10. Air is admitted into the discharge gap 12 in thedirection of the arrow A and ozone is formed within said gap 12 from theoxygen contained in the air. Cooling of the discharge gap is carried outby circulation of water around the metal tube 10 through ducts 13.

The diameter of the passageway 5 which is formed at the center of theplug 4 is slightly larger than the diameter of the rod 6 of the brush 7.Since the diameter of the passageway Sis slightly larger than that ofthe rod 6, a flow of air is admitted into the dielectric tube 1, therebyproducing a renewal of air and appreciably enhanced cooling of thedielectric, there being consequently no further danger of destruction ofthe newly formed ozone under the action of heat emitted as a result ofoperation of the device.

In order to increase the flashover distance between the metal coating 2and the metal tube 10, it would also be possible as shown in FIG. 2 toplace a plug 4 which is identical with the plug hereinabove described atthat end of the dielectric tube 1 which is remote from the supply.

An apparatus for the production of ozone is usually equipped with anappreciable number of dielectrics and it appears advantageous to makeprovision for a uniform distribution of the overall air flow within allthe discharge gaps. Since it is not possible to obtain such a uniformdistribution by natural means by reason of the low rates of flow withinthe discharge gaps (of the order of 2 mm./second), an advantageousexpedient in accordance with the invention therefore consists in the useof a plug 14 of the type illustrated in FIGS. 3 and 4. This plug 14 doesnot penetrate into the dielectric tube 1 as in FIGS. 1 and 2 but isfitted over the extremity of said tube. A passageway for the rod 6 ofthe brush 7 is pierced within said plug I4 and this latter is preferablyprovided in addition with lateral ducts 16 in order that a communicationmay thus be established between the chamber 17 into which air isadmitted and the discharge gaps 12. The diameter of the ducts I6 iscalculated in order to produce a pressure drop such that the total flowis uniformly distributed between all the passageways and ducts.

The plug 14 can usefully be provided with centering nipples 18 whichserve to maintain the requisite spacing between the dielectric tube 1and the metal tube 10. As in the case of the plug illustrated in FIGS. 1and 2, said plug 14 is also provided with an O-ring seal 19 and withexternal corrugations 20.

As was the case with the embodiment shown in FIGS. 1 and 2, theflashover distance between the metal coating 2 and the metal tube 10 isincreased by placing an additional plug 14 at the other end of thedielectric tube 1.

No matter what forms of embodiment. application or utilization may beadopted, it is clear from the foregoing description that the dielectricswhich are thus obtained for use in ozone-generating appliances ascompared with the dielectrics employed for the same purpose in the priorart provide substantial advantages in addition to those mentionnedearlier, and in particular: I

the advantage of avoiding embnttlement m the end portions of dielectrictubes while permitting the fabrication of dielectric tubes of insulatingmaterial having small thickness and high permittivity.

The advantage of additional cooling which is carried out by circulatingair within the interior of the dielectric tube and which is added to theexternal cooling by water circulation, thus completely eliminating anydanger of destruction of the ozone which is formed in the apparatus.

As is clearly brought out in the foregoing, the invention is not limitedin any sense to those forms of embodiment and application which havejust been described in detail. On the contrary, all alternative formswhich may become apparent to any one versed in the art can be consideredto come within the broad purview of this invention.

What I claim is:

1. An assembly for a generating apparatus of ozone comprising acylindrical tube of insulating material, a metal interior covering insaid cylindrical tube, said tube having a constant thickness and beingopen at its two ends, said ends being internally non-metallized ends, aremovably plug of insulating material resistant to ozone closing atleast one of said ends, said plug having an axial orifice, a metallicrod extending through said orifice to the interior of said tube, meansupon said rod providing electrical contact with said interior covering,said orifice having a diameter slightly more than the diameter of saidrod and said plug having upon its external portion corrugations to avoidflashover phenomena and a spring joint between said plug and said tubeto assure the maintenance in place of said plug with the end of saidtube which it closes.

2. Dielectric according to claim 1 wherein said plug is enclosed withinthe corresponding end of said tube of insulating material.

3. Dielectric according to claim I wherein said plug covers thecorresponding end of the tube of insulating material.

4. Dielectric according to claim 3 wherein said plug has lateralsupplementary orifices which place in communication the chamber in whichis admitted the air and the discharge intervals.

5. Dielectric according to claim 3 wherein said plug has centeringprojections for said dielectric tube in a metallic tube in which it ismounted.

6. Dielectric according to claim I wherein the other end of said tubeofinsulating material is also closed by a plug.

1. An assembly for a generating apparatus of ozone comprising acylindrical tube of insulating material, a metal interior covering insaid cylindrical tube, said tube having a constant thickness and beingopen at its two ends, said ends being internally non-metallized ends, aremovably plug of insulating material resistant to ozone closing atleast one of said ends, said plug having an axial orifice, a metallicrod extending through said orifice to the interior of said tube, meansupon said rod providing electrical contact with said interior covering,said orifice having a diameter slightly more than the diameter of saidrod and said plug having upon its external portion corrugations to avoidflashover phenomena and a spring joint between said plug and said tubeto assure the maintenance in place of said plug with the end of saidtube which it closes.
 2. Dielectric according to claim 1 wherein saidplug is enclosed within the corresponding end of said tube of insulatingmaterial.
 3. Dielectric according to claim 1 wherein said plug coverstHe corresponding end of the tube of insulating material.
 4. Dielectricaccording to claim 3 wherein said plug has lateral supplementaryorifices which place in communication the chamber in which is admittedthe air and the discharge intervals.
 5. Dielectric according to claim 3wherein said plug has centering projections for said dielectric tube ina metallic tube in which it is mounted.
 6. Dielectric according to claim1 wherein the other end of said tube of insulating material is alsoclosed by a plug.